Low-Frequency-Stabilized Electric Field Integral Equation on Topologically Non-Trivial Geometries for Arbitrary Excitations

The low-frequency preconditioned electric field integral equation (EFIE) based on quasi-Helmholtz decompositions is widely used to determine the radiated or scattered field by a given structure over a wide frequency range. However, if the excitation source is not a plane wave but, for instance, a line current, the standard preconditioners cannot recover all current components required to accurately obtain the fields. In this work, we propose an adaptive frequency normalization scheme of the discretized system that overcomes this problem irrespective of the specific excitation and irrespective of the underlying topology of the structure. To this end, the appropriate scaling factors are derived solely based on the norms of the right-hand side (RHS) components. Numerical results demonstrate the importance of our approach to obtain accurate results.